A wind power generator comprises a rotor configured to rotate by wind, a drive train to convert rotational force into power, and a tower and foundation to support the rotor and the drive train. Because a wind power generator is installed at neighboring sea or deep sea, significant differences in time and costs spent for installation occur depending upon sea environmental conditions and climate conditions. Accordingly, shortening of installation period at sea is a core technology in design of an offshore wind power generator.
A conventional offshore wind power generator is installed at sea such that a blade, rotor and nacelle assembly and tower sections are separately transported to an installation area in the sea by ships and are assembled together at sea. Recently, an offshore wind power generator installation method to reduce a period of installing a wind power generator at sea has been developed, in which all turbine components except a foundation are previously assembled on the land, transported to an installation area, and joined to an offshore foundation by lifting the whole wind power generator.
In general, when installing such a preassembled wind power generator at sea, a lower part of a tower of the wind power generator is lifted using a transport machine such as a crane, and the wind power generator is transported and engaged with a joining part of an offshore foundation.
However, in the installation method of lifting a lower part of the wind power generator using a crane and transporting the same, a center of gravity of the wind power generator is not positioned at the center of the tower of the wind power generator, and is positioned at an eccentric position from the center of the tower toward the blade of the wind power generator.
Accordingly, in order to prevent the wind power generator from turning over, the wind power generator should be lifted tilting rearward. However, it is difficult to install the wind power generator if lifted in a tilted state.
Further, lifting the wind power generator in a tilted state may cause decrease in safety due to a risk of the wind power generator overturning while the same is moved and quality deterioration due to damage of inner components, oil leakage or the like.
Additionally, in order to keep a balance of the wind power generator that is lifted and transported in a tilted state, it is necessary to provide an additional spreader beam at a middle of the wind power generator in order to support the tower, which may cause increase in installation costs and weight of the wind power generator and damage of a non-reinforced thin portion of the tower which is in contact with the spreader beam if the balance is lost during transport.